I've written a small patch that allows dwm to swap the contents of two tags.

As this is my first time actually hacking into dwm's code I'm looking
forward to receiving some feedback. Also, if more people find this
useful I would like to make it publicly available in
https://dwm.suckless.org/patches/ .

I sent this patch to dev_AT_suckless.org but I think it belongs better here.